SeaMonkey is a software package which is derived from the application formerly known as Mozilla Application Suite. It features a state-of-the-art web browser and powerful email client, as well as a WYSIWYG web page composer and a feature-rich IRC chat client. For web developers, mozilla.org's DOM inspector and JavaScript debugger tools are included as well. SeaMonkey is indeed one of the most complete, powerful, and secure internet software packages available today.

SeaMonkey comes with the the look and feel familiar to users of its predecessors, the Mozilla Application Suite and Netscape Communicator packages, but adds many new features as well as back-end changes that improve security, stability and performance. Some highlights are: drag&drop reordering of tabs, phishing e-mail detection, support for a single shared inbox when using multiple accounts, and support for Scalable Vector Graphics (SVG).